Taxonomy

Kingdom:

Phylum:

Class:

Affinity:

Eiffelia is thought to fall near the divergence of the calcareous and hexactinellid sponges (Botting and Butterfield, 2005).

Species name:

Eiffelia globosa

Described by:

Walcott

Description date:

1920

Etymology:

Eiffelia – from the nearby Eiffel Peak, named on account of its resemblance to Paris’ Eiffel Tower. The tower bears the name of Alexandre Gustave Eiffel (1832-1923), a French engineer famous for building many large steel structures.

globosa – from the Latin globus, “globe or ball,” reflecting the organism’s shape.

Localities

Principal localities:

History of Research

Brief history of research:

Originally described by Walcott in 1920, little research concentrated on Eiffelia until it was re-described by Rigby in 1986 as part of his review of Burgess Shale sponges. Additional specimens collected by the Royal Ontario Museum were described subsequently by Rigby and Collins (2004). Bearing characteristics of both the calcareous and hexactinellid sponges, Eiffelia has been important in determining higher-level evolutionary relationships within the sponges. Eiffelia spicules form by the accretion of phosphate on a siliceous core, which provides a possible evolutionary transition between the minerals used in the construction of spicules (Botting and Butterfield, 2005)

Description

Morphology:

Eiffelia is usually preserved as a flattened net of spicules within a single layer, forming a mesh with an approximately circular outline 1 to 6 cm in diameter. Spicules occur in at least five distinct size ranges. The largest ones usually take the form of six-pointed stars (hexaradiate), whereas the smallest ones usually have only four-pointed ends. The rays generally run parallel to one another, producing a somewhat geometric lattice-like appearance. The largest spicules, spaced a few millimetres apart from one another, enclose spicules of the second size class between their slender tapering rays. The smaller spicules, which are so small as to rarely be preserved, fill the remaining gaps in the mesh. The spicules themselves are joined by a small central disc formed from flared-out sections of their bases at the point where the six spines meet. Eiffelia’s spicules supported a thin wall that would have formed an orb-shaped sac perforated with occasional small elliptical openings (ostia).

Abundance:

Relatively rare in the Walcott Quarry where it represents only 0.1% of the Walcott Quarry community (Caron and Jackson, 2008).